1. Field of the Invention
This invention relates to an optical particle analyzing apparatus for irradiating with light a flow of particles in a specimen such as cells suspended in a liquid, detecting scattered light or fluorescence emitted by individual particles, and classifying and enumerating the cells. More particularly, the invention relates to an optical particle analyzing apparatus employing both a laser light source and a lamp light source as the irradiating light sources.
2. Description of the Prior Art
The classification and enumeration of particles such as white blood cells or reticulocytes contained in blood is a necessary and useful tool in clinical analysis, and the trend recently is to use an automatic particle analyzing apparatus for this purpose. In an analyzing apparatus of this kind, a blood specimen is drawn up from a specimen suction unit, the specimen is pretreated automatically within the apparatus and delivered to a detector, and signals detected by the detector are counted and analyzed to obtain an output of the number and content of prescribed cells. One example of such an apparatus is a flow cytometer, in which the blood specimen is diluted and stained to obtain a specimen solution that is then passed through the central portion of a flow cell in the form of a fine stream. A detecting zone is formed by irradiating a portion of the fine stream with a narrow beam of light from a light source, and a change in scattered light or fluorescence generated whenever individual blood cells pass through the detecting zone is detected by a photodetector. By way of example, a two-dimensional distribution, in which scattered light intensity and fluorescent light intensity are plotted along two axes, is formed from the detected signals, and each of the particles is classified and counted by setting demarcation lines in the two-dimensional distribution. For example, reticulocytes are demarcated from mature red blood cells or platelets and the number or ratio of the reticulocytes is obtained. An argon laser often is used as the light source.
In the conventional flow cytometer, the argon laser is used as a light source for exciting particles to fluorescence. The reason for this is that light in the blue region and having a comparatively short wavelength is required to be used as the excitation light in order to produce fluorescence. However, an argon laser is high in cost, and not only does the laser itself occupy a large amount of space, but the peripheral equipment for the laser such as the power supply for driving the laser, also is large in size. Another problem is that a large amount of power is consumed overall.
Though it is preferred to use small-size, inexpensive light-source equipment instead of an argon laser for the purpose of producing fluorescence, a semiconductor laser capable of emitting light in the blue region is not available at the present time. Of course there are semiconductor lasers which produce light in the red through infrared regions, but fluorescence cannot be obtained with light sources that operate in these wavelength regions.